1. Field of the Invention
This invention relates to a colored film, and more specifically to a colored film excellent in vividness, transparency, light resistance, stability and the like.
2. Description of the Related Art
For many years, colored films have been used widely in vehicles, buildings, etc. and also as wrapping materials, display materials and the like. These colored films are used for the purpose of ornamentation, selection of desired incident light wavelengths, prevention of visibility from the outside, or the like, for example, to use them for the purpose of solar control, they are required to have excellent vividness, transparency, light resistance, stability and the like. Further, they are also required to permit easy bonding and pealing. Accordingly, each transparent film is provided on one side thereof with a layer composed of a pressure-sensitive adhesive, a heat-sensitive adhesive or the like. Incidentally, the term "pressure-sensitive adhesive" as used herein should be construed to embrace therein an autohesive (which is a material having no surface tackiness but having a property of being bonded to a smooth surface, such as a glass pane, metal plate, coated surface or plastic plate, by making use of air tightness between the smooth surface and a surface of the autohesive, that is, between these mirror-like surfaces; which will hereinafter be called simply an "autohesive").
For coloration, it has been the conventional practice to use adhesive-soluble dyes in view of the requirement for transparency. Although it is not impossible to color a transparent film itself with a dye, this is very difficult. Coloration is therefore applied primarily to such pressure-sensitive adhesive, heat-sensitive adhesive or curable adhesive.
According to the above-described conventional art, the coloration of an adhesive with a dye is easy, and a colored film excellent in vividness and transparency is available. The colored film is however accompanied by a problem such that, when the colored film is used under conditions where it is exposed to outdoor light like a solar control film, for example, it fades or discolors after an elapse of a certain time as the dye has poor light resistance. With a view to overcoming these problems, a variety of proposals making use of pigments instead of dyes have been made. Such conventional techniques can provide colored films having excellent light resistance, but still cannot furnish color films having satisfactory vividness and transparency because pigments can hardly be dispersed as fine particles in adhesives and, even if dispersed, the thus-dispersed pigment particles tend to undergo considerable aggregation.